Has anybody come across a list of ARM & THUMB instructions that cause deviation from the linear instruction stream?
I've been trying to figure out gdb-stub single stepping using software interrupts, and in single stepping you need to find
the next instruction(s) where the next breakpoint instruction needs to be set.
There are three cases:
1) current instruction doesn't change the execution path. Next instruction is the next word.
2) current instruction is a jump. The operand defines the next instruction address
3) current instruction is conditional branch. One possible next instruction is the next word, the other possible
instruction address is defined by the operand. (That includes conditional add with PC as the target, and the like).
To implement single stepping, I need to tell those cases apart and figure out how to find out the possible branching address.
I could go through manuals of numerous processors instruction by instruction and maybe I'd be done within the next couple of years,
or I could find a list of instructions to check, or a paper that explains how to "decode" the instructions in a useful way.
Also, there doesn't seem to be lots of sources of ARM gdb servers or stubs around that use software breakpoints.
If you're lucky, you can place instructions that are used often in the beginning of the table
You read my mind.
But ARM's instruction set is not too complicated either.
Assembly is not, but the encoding is.
and:
Oh, and for small assembly routines I've been using inline asm, like
void rpi2_trap_handler()
{
// IRQs need to be enabled for serial I/O
asm volatile (
"push {r0}\n\t"
"mrs r0, cpsr\n\t"
"bic r0, #128 @ enable irqs\n\t"
"msr cpsr, r0\n\t"
"pop {r0}\n\t"
);
gdb_trap_handler();
}
: